U.S. patent application number 15/976979 was filed with the patent office on 2018-09-13 for systems and methods for security sensing in a power cable for an article of merchandise.
The applicant listed for this patent is InVue Security Products Inc.. Invention is credited to Jonathon D. Phillips, Justin A. Richardson, Gary A. Taylor.
Application Number | 20180261058 15/976979 |
Document ID | / |
Family ID | 53681919 |
Filed Date | 2018-09-13 |
United States Patent
Application |
20180261058 |
Kind Code |
A1 |
Richardson; Justin A. ; et
al. |
September 13, 2018 |
SYSTEMS AND METHODS FOR SECURITY SENSING IN A POWER CABLE FOR AN
ARTICLE OF MERCHANDISE
Abstract
Embodiments of the present invention are directed to merchandise
security systems and methods for displaying and protecting an
article of merchandise from theft. In one example, the system
includes a sensor configured to be secured to the article of
merchandise, wherein the sensor includes alarming circuitry. The
system also includes a tether comprising a pair of conductors
electrically connected to the alarming circuitry, wherein the pair
of conductors is configured to transfer power to the sensor and/or
to the article of merchandise. In response to power ceasing to be
transferred, the alarming circuitry is configured to monitor an
electrical signal transmitted through the pair of conductors in
order to determine whether the tether has been cut or removed from
the sensor.
Inventors: |
Richardson; Justin A.;
(Waxhaw, NC) ; Phillips; Jonathon D.; (Fort Mill,
SC) ; Taylor; Gary A.; (Fort Mill, SC) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
InVue Security Products Inc. |
Charlotte |
NC |
US |
|
|
Family ID: |
53681919 |
Appl. No.: |
15/976979 |
Filed: |
May 11, 2018 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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15667284 |
Aug 2, 2017 |
9972178 |
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15976979 |
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15111626 |
Jul 14, 2016 |
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PCT/US2015/012378 |
Jan 22, 2015 |
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15667284 |
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61930529 |
Jan 23, 2014 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
G08B 13/1463 20130101;
G06Q 30/0185 20130101; G08B 13/1454 20130101 |
International
Class: |
G08B 13/14 20060101
G08B013/14 |
Claims
1-21. (canceled)
21. A merchandise security system for displaying and protecting an
article of merchandise comprising: a sensor configured to attach to
the article of merchandise and to detect removal of the article of
merchandise from the sensor, the sensor comprising an upper portion
and a lower portion; a power cable having a connector configured to
operably engage an input port on the article of merchandise for
providing power to the article of merchandise, wherein the lower
portion is configured to connect to an end of the power cable
opposite the connector, wherein the upper portion is configured to
receive one or more retaining arms for engaging the article of
merchandise, wherein the upper portion is configured to attach to
the article of merchandise and the lower portion such that the
upper portion is disposed between the lower portion and the article
of merchandise and at least a portion of the end of the power cable
is disposed between the upper portion and the lower portion; a base
configured to removably support the sensor thereon such that the
sensor is removable from the base and positionable on the base; and
a tether connected to the sensor, wherein the base is configured to
receive the tether.
22. The merchandise display system of claim 21, wherein the lower
portion comprises a recess configured to receive the end of the
power cable.
23. The merchandise display system of claim 22, wherein the end of
the power cable received within the recess is configured to be
disposed between the upper portion and the lower portion.
24. The merchandise display system of claim 22, wherein the end of
the power cable is enlarged relative to a diameter of the
cable.
25. The merchandise display system of claim 22, wherein the recess
is defined in a surface of the lower portion configured to be
secured to the article of merchandise.
26. The merchandise display system of claim 21, wherein the lower
portion comprises a top surface and a side surface, and wherein the
end of the cable is configured to be received on the top surface
and to extend through a slot defined in the side surface.
27. The merchandise display system of claim 21, wherein the tether
is coupled to a recoiler such that the tether is extendable and
retractable relative to the base.
28. The merchandise display system of claim 27, further comprising
a power source electrically connected to the recoiler.
29. The merchandise display system of claim 21, wherein the tether
comprises a plurality of conductors for communicating with the
sensor.
30. The merchandise display system of claim 21, wherein the upper
portion comprises a pair of slots each configured to receive a
respective retaining arm.
31. The merchandise display system of claim 21, wherein the lower
portion is configured to be secured to the upper portion with at
least one fastener.
32. The merchandise display system of claim 21, wherein the lower
portion is configured to be secured to the upper portion such that
the one or more retaining arms are secured therebetween and cannot
be removed without first detaching the lower portion from the upper
portion.
33. The merchandise display system of claim 21, wherein the upper
portion comprises a contact, limit, or pressure switch configured
to detect when the article of merchandise has been removed from the
sensor.
34. The merchandise display system of claim 21, further comprising
alarming circuitry configured to detect the sensor being removed
from the article of merchandise, the tether being removed from the
sensor, and/or the tether being cut.
35. The merchandise display system of claim 33, wherein the sensor
is configured to wirelessly communicate with a key for arming
and/or disarming the alarming circuitry.
36. The merchandise display system of claim 21, wherein the tether
comprises a connector at one end configured to be releasably locked
to the sensor such that the connector cannot be removed from the
sensor without first being unlocked.
37. A merchandise security system for displaying and protecting an
article of merchandise comprising: a sensor configured to attach to
the article of merchandise and to detect removal of the article of
merchandise from the sensor, the sensor comprising an upper portion
and a lower portion; and a power cable having a connector
configured to operably engage an input port on the article of
merchandise for providing power to the article of merchandise,
wherein the lower portion comprises a recess configured to receive
an end of the power cable opposite the connector, wherein the upper
portion is configured to receive one or more retaining arms for
engaging the article of merchandise, wherein the upper portion is
configured to attach to the article of merchandise and the lower
portion such that the upper portion is disposed between the lower
portion and the article of merchandise and at least a portion of
the end of the power cable is disposed between the upper portion
and the lower portion.
38. A method for displaying and protecting an article of
merchandise comprising: securing an upper portion of a sensor to an
article of merchandise, the sensor configured to detect removal of
the article of merchandise from the sensor; engaging one or more
retaining arms received by the upper portion to the article of
merchandise; connecting an end of a power cable to a lower portion
of the sensor; operably engaging a connector of the power cable
opposite the end with an input port on the article of merchandise
for providing power to the article of merchandise; and securing the
lower portion to the upper portion such that the upper portion is
disposed between the lower portion and the article of merchandise
and at least a portion of the end of the power cable is disposed
between the upper portion and the lower portion.
39. The method of claim 38, further comprising: releasably
connecting a tether to the lower portion of the sensor with a
connector at one end; and locking the connector to the sensor with
a lock mechanism such that the connector cannot be removed from the
sensor without first disengaging the lock mechanism.
40. The method of claim 38, wherein connecting comprises inserting
the end within a recess defined in the lower portion.
Description
CROSS REFERENCE To RELATED APPLICATION
[0001] This application is a continuation of U.S. application Ser.
No. 15/667,284, filed Aug. 2, 2017, which is a divisional of U.S.
application Ser. No. 15/111,626 filed on Jul. 14, 2016, which is a
national phase entry of International Application No.
PCT/US2015/012378, filed Jan. 22, 2015, which claims the benefit of
priority to U.S. Provisional Application No. 61/930,529 filed on
Jan. 23, 2014, the entire disclosures of which are incorporated
herein by reference.
FIELD OF THE INVENTION
[0002] Embodiments of the present invention relate generally to
security systems and methods for displaying articles of merchandise
in a retail environment. More particularly, the invention relates
to systems and methods for security sensing in a tether for an
article of merchandise.
BACKGROUND OF THE INVENTION
[0003] Retailers routinely display articles of merchandise, such as
telephones, portable computers (e.g. notebooks, laptops, tablets,
etc.), e-readers, media players, and the like for customers to
evaluate before making a purchase. These articles of merchandise
are continually being made smaller and lighter in weight due to
advances in technology and materials. As a result, such merchandise
is increasingly vulnerable and susceptible to theft. At the same
time, the retail price, and hence the profit margin, for such
merchandise continues to decline. Accordingly, these articles of
merchandise need to be secured by a security device that
effectively and cost efficiently protects the merchandise from
theft.
[0004] It is common in the field of retail merchandise security to
tether electronic devices to a store fixture to prevent theft, yet
still allowing a customer to interact with the device. The
retailers and their customers want these tethers to be as
unobtrusive as possible, making smaller diameter tethers desirable.
One problem with keeping tether size small is the number of
conductors needed to supply power and sensing signals. Typically, a
plurality of conductors is needed to provide both power and
security. As a result, reducing the number of conductors while
maintaining necessary functionality and security can be
challenging.
SUMMARY OF THE INVENTION
[0005] In one aspect, the invention is a merchandise security
system for displaying and protecting an article of merchandise. The
system includes a sensor configured to be secured to the article of
merchandise, wherein the sensor including alarming circuitry. The
system further includes a tether including a pair of conductors
electrically connected to the alarming circuitry, wherein at least
one of the pair of conductors is configured to transfer power to
the sensor and/or to the article of merchandise. In response to
power ceasing to be transferred, the alarming circuitry is
configured to monitor an electrical signal transmitted through the
pair of conductors in order to determine whether the tether has
been cut or removed from the sensor.
[0006] In one embodiment, the pair of conductors consists of a
positive power conductor and a negative ground conductor. In
another embodiment, the tether is coupled to a recoiler such that
the tether is extendable and retractable relative to the recoiler.
In yet another embodiment, each of the sensor and the recoiler has
at least one resistor electrically connected to the pair of
conductors in a sense loop circuit, and the alarming circuitry is
configured to determine a change in resistance in the sense loop
circuit. In still another embodiment, the alarming circuitry and
the pair of conductors define the sense loop circuit, and the
resistor in the recoiler is disposed across the pair of conductors.
In still another embodiment, the alarming circuitry is configured
to generate a visual and/or an audible alarm signal in response to
the sensor being removed from the article of merchandise, the
tether being removed from the sensor, and/or the tether being
cut.
[0007] In another aspect, the invention is a method for displaying
and protecting an article of merchandise. The method includes
transferring power through a tether to a sensor attached to the
article of merchandise and/or to the article of merchandise,
wherein the tether includes a pair of conductors electrically
connected to the sensor. The method further includes monitoring, in
response to power ceasing to be transferred, an electrical signal
transmitted through the pair of conductors in order to determine
whether the tether has been cut or removed from the sensor.
[0008] In one embodiment monitoring includes repeatedly determining
a voltage level in predetermined increments of time. In another
embodiment, determining includes determining whether the voltage
level is greater than a predetermined voltage level. In yet another
embodiment, the method further includes generating a visual and/or
an audible alarm signal when the voltage level is greater than the
predetermined voltage level. In still another embodiment, the
method further includes repeating the step of determining the
voltage level if the voltage level is greater than the
predetermined voltage level. In still another embodiment, the
method further includes generating the electrical signal on the
pair of conductors prior to determining the voltage level. In still
another embodiment, monitoring includes determining a change in
total resistance in a sense loop circuit defined at least by the
sensor, the pair of conductors, and a plurality of resistors. In
still another embodiment, the method further includes determining
whether the pair of conductors has been shorted.
BRIEF DESCRIPTION OF THE DRAWING FIGURES
[0009] The detailed description of the invention provided hereafter
may be better understood with reference to the accompanying drawing
figures, in which embodiments of a merchandise security system for
displaying an article of merchandise are disclosed, and in which
like reference characters indicate the same or similar parts.
[0010] FIG. 1 is a perspective view of a merchandise security
system for displaying and protecting an article of merchandise
according to an embodiment of the invention.
[0011] FIG. 2 is a perspective view of another embodiment of a
merchandise security system according to the invention shown with
the article of merchandise and a sensor attached thereto removed
from a base.
[0012] FIG. 3 is a perspective view showing the merchandise
security system of FIG. 2 electrically connected to a recoiler
secured to a support surface of a display fixture and electrically
connected to an external source of power.
[0013] FIG. 4 is a perspective view of the merchandise security
system of FIG. 3 showing the recoiler detached from a mounting
plate secured to the support surface of the display fixture.
[0014] FIG. 5 is an exploded perspective view showing an embodiment
of a sensor for use with a merchandise security system according to
the invention.
[0015] FIG. 6 is an exploded perspective view of the sensor of FIG.
5 shown with an upper portion of the sensor attached to an article
of merchandise and a lower portion of the sensor detached from the
upper portion.
[0016] FIG. 7 is a perspective view of another embodiment of a
sensor for use with a merchandise security system according to the
invention shown with an upper portion of the sensor detached from a
lower portion of the sensor.
[0017] FIG. 8 is a perspective view of a portion of the merchandise
security system of FIG. 1 illustrating the use of a key to arm
and/or disarm the alarming circuitry of the sensor.
[0018] FIG. 9 is a schematic illustrating a pair of conductors
configured for transmitting electrical power to the sensor and/or
the article of merchandise according to the invention.
[0019] FIG. 10 is a schematic illustrating a sense loop circuit for
generating an alarm signal according to the invention.
[0020] FIG. 11 is a graph depicting the voltage in the sense loop
circuit of FIG. 10 when a tether is intact and there is a loss of
electrical power.
[0021] FIG. 12 is a graph depicting the voltage in the sense loop
circuit of FIG. 10 when the tether has been cut or removed.
[0022] FIG. 13 is a graph depicting the voltage in the sense loop
circuit of FIG. 10 for an intact and connected tether, referred to
as a "good cable," and a cut or removed tether, referred to as a
"bad cable."
[0023] FIG. 14 is a graph depicting an example of the voltage in
the sense loop circuit of FIG. 10 where the voltage level is
initially at an input power level and thereafter the input power
ceases.
[0024] FIG. 15 is a graph depicting another example of the voltage
in the sense loop circuit of FIG. 10 where the voltage level is
initially at the input power level and thereafter input power
ceases.
[0025] FIG. 16 is a flowchart of a method for displaying and
protecting an article of merchandise according to an embodiment of
the invention.
DETAILED DESCRIPTION OF EMBODIMENTS OF THE INVENTION
[0026] One or more embodiments of a merchandise security system for
displaying an article of merchandise are shown in the accompanying
drawing figures and described below. The article of merchandise,
indicated generally herein by reference character M, is typically a
display model or an operational sample of electronic merchandise,
such as portable telephones, smart phones, computers (e.g.
notebooks, laptops, tablets, etc.), e-readers, media players, and
the like, for a customer to examine before making a decision
whether to purchase the article. The article of merchandise is
typically displayed in a manner that permits a prospective
purchaser to evaluate the operation and features of the
merchandise, while protecting the merchandise from theft. In one
embodiment, a sensor with alarming circuitry may be attached to the
article of merchandise for detecting various alarming conditions,
such as the article being removed from the sensor. A tether may be
operably engaged with the sensor at one end, while the opposite end
may be secured to a base or to a surface of a display fixture. As
explained in further detail below, the alarming circuitry of the
sensor may also be configured to detect an alarming condition of
the tether, such as a cutting, severing, removing or detaching of
the tether. As also explained in further detail below, the tether
may consist of only a pair of conductors. Thus, unlike conventional
tethers that include three, four, or more conductors, the tether
according to one embodiment may have only two conductors for
providing both power and security functionality. Regardless, the
alarming circuitry is configured to monitor an electrical signal in
the conductors in order to determine if an alarming condition has
occurred.
[0027] FIGS. 1-4 illustrate embodiments of a merchandise security
system, indicated generally herein by reference character 10, for
displaying an article of merchandise M and securing the merchandise
from theft or unauthorized removal. The system 10 generally
includes a sensor 12, a tether 14, a base 16, and a recoiler 18, as
shown in the embodiment of FIGS. 2-4. The sensor 12 is configured
to be secured to the article of merchandise M, such as with a
pressure-sensitive adhesive. Alternatively, or in addition, the
sensor 12 may be secured to the article of merchandise M by two or
more retaining arms 34, as illustrated in the embodiment of FIG. 1.
A first end of the tether 14 may be electrically connected to the
recoiler 18, as shown in FIG. 4, while the opposite second end of
the tether may include a jack or connector 22 for electrically
connecting the tether to the sensor 12, as shown in FIG. 2. Thus,
connector 22 may be releasably engaged with sensor 12 to establish
electrical communication therebetween. The connector 22 may be
further secured in position with a lock mechanism 21, such as a
clip, as indicated by the arrow in FIG. 2. As such, when lock
mechanism 21 is engaged with connector 22, the connector may not be
removed from the sensor 12 without first disengaging the lock
mechanism. The lock mechanism 21 may allow tension to be applied to
the tether 14 without causing the connector 22 to become
inadvertently disconnected from the sensor 12. Furthermore, the
lock mechanism 21 may provide stress relief for the electrical
connection between the sensor 12 and the tether 14.
[0028] The base 16 is configured to removably support the sensor 12
thereon such that a prospective purchaser may remove the article of
merchandise M and the sensor secured thereto from the base for
inspection, and subsequently return the merchandise to the base for
display. The base 16 may define an opening 15 therethrough that
allows the tether 14 to extend and retract relative to the base.
Recoiler 18 may be disposed within the base 16, or alternatively,
the recoiler may be secured below a support surface 20 (e.g., a
counter, shelf, or the like) of a display fixture, as shown in FIG.
3. In this regard, the recoiler 18 may include a mounting plate 23
that is configured to be secured to the underside of the support
surface 20, in which case the recoiler is configured to engage the
mounting plate and be secured thereto. As shown in FIG. 3 and
illustrated schematically in FIG. 10, the recoiler 18 may be
electrically connected to a power source 24 via an input power
cable 25 that is configured to provide power to the recoiler and to
the tether 14. A plug or other connector, for example, an AC power
plug and AC/DC power converter, may be disposed at a first end of
the input power cable 25 for electrically connecting the input
power cable to an external source of electrical power, for example,
a conventional 110V AC power outlet. A second opposite end of the
input power cable 25 may be electrically connected to an input
cable 27 of the recoiler 18. In some embodiments, the sensor 12 is
also electrically connected to a power cable 26 that is configured
to provide electrical power to the article of merchandise M, as
shown in FIG. 2. Thus, the power cable 26 may be utilized to
facilitate demonstration of the operation of the article of
merchandise M on display, as well as for charging a rechargeable
battery of the merchandise. FIG. 2 further shows that the power
cable 26 may include a connector 28 that is configured to operably
engage an input port provided on the article of merchandise M. In
some embodiments, the alarming circuitry of the sensor 12 may be
configured to detect removal of the connector 28 and to generate an
audible and/or a visual alarm signal in response to removal of the
connector 28 from the sensor 12.
[0029] As discussed above, the sensor 12 may include alarming
circuitry, a processor, a central processing unit, or the like,
that is configured to determine whether various security events
have occurred for generating an audible and/or a visual alarm
signal. The sensor 12 may also include an alarm (e.g., a
piezoelectric device) that is configured to generate an audible
alarm. Thus, the sensor 12 may be configured as "alarm-on-product,"
whereby the sensor is operable to alarm when attached to the
article of merchandise M and/or when detached from the article of
merchandise. In some cases, the sensor 12 may include a visual
indicator (e.g., an LED) for indicating the alarming circuitry is
armed and/or alarming. Moreover, the sensor 12 may include a
transfer port 30 that is configured to communicate with a key 32
(see, FIG. 8) for arming and/or disarming the alarming circuitry.
In one embodiment, the transfer port 30 is configured to
communicate wirelessly with key 32 to determine whether the key is
authorized to arm and/or disarm the alarming circuitry. According
to some embodiments, the key 32 is similar to that described in
U.S. Pat. No. 7,737,845, the contents of which are hereby
incorporated by reference in their entirety. According to one
embodiment, the sensor 12 may include a contact, limit or pressure
switch 33 (see, FIG. 7), or the like, that is configured to detect
when the article of merchandise M has been removed from the sensor.
The alarming circuitry may be configured to detect the removal of
the article of merchandise M from the sensor 12 and to generate and
an audible and/or a visual alarm signal in response thereto.
[0030] In some embodiments, the sensor 12 is a one-piece design
that is configured to be attached to the article of merchandise M.
FIGS. 5-8 illustrate embodiments wherein the sensor 12 may include
an upper portion 35 and a lower portion 37. The upper portion 35
may be configured to be secured to the lower portion 37, such as
with a proprietary fastener 39. In addition, the upper portion 35
may be configured to be secured to the article of merchandise M,
while the lower portion 37 may be configured to receive the
connector 22. FIG. 7 shows that a first end of the power cable 26
may be enlarged and configured to be inserted into a recess 31
formed in the lower portion 37, which secures the power cable
therein when the upper portion 35 and the lower portion 37 are
secured together. In addition, FIG. 6 shows that upper portion 35
may include an engagement member 40 and FIG. 7 shows that lower
portion may include an opening 42 configured to receive the
engagement member therein. Engagement between the engagement member
40 and the opening 42 may be used to align the upper portion 35 and
the lower portion 37 relative to one another prior to securing the
upper and lower portions together.
[0031] Furthermore, FIGS. 1, 5-6, and 8 illustrate that sensor 12
may include one or more retaining arms 34 for securing the article
of merchandise M to the sensor. In one example, FIG. 5 shows that
the upper portion 35 may include a pair of slots 36 that are each
configured to receive a respective retaining arm 34 therein. Thus,
retaining arms 34 may be configured to slide within the slots 36 to
adjust the position of the retaining arms relative to the width or
length of the article of merchandise M. As illustrated by FIGS.
5-6, the lower portion 37 may be secured to the upper portion 35
such that the retaining arms 34 are secured therebetween and cannot
be removed without first detaching the lower portion from the upper
portion.
[0032] Embodiments of the present invention provide for the
delivery of electrical power to the article of merchandise M and/or
to the sensor 12 through a pair of conductors 50 (see, e.g., FIG.
9) disposed within the tether 14 (removed for purposes of clarity).
In some examples, the tether 14 includes only two conductors 50,
such as a positive power line and a ground line. An input power
source 24 may be in electrical communication with the conductors 50
for transmitting power through the tether 14 and to the article of
merchandise M and/or the sensor 12. In order to obtain a sense
signal using only the power lines, one technique is to simply
detect when the electrical power stops flowing. The problem with
this method is that the sensor 12 and/or the article of merchandise
M typically do not receive power when there is a power outage,
which could cause a false alarm in the merchandise security system
10. Instead, one embodiment of the invention provides security
sensing over the same conductors 50 used to supply power to the
article of merchandise M and/or the sensor 12. As such, the
diameter of the tether 14 may be reduced in comparison to
conventional tethers, and the incidence of false alarms may be
reduced.
[0033] According to some embodiments, the merchandise security
system 10 utilizes a security scan for determining whether the
tether 14 has been cut or removed from the sensor 12, and/or
whether the power cable 26 has been removed from the article of
merchandise M. This scan may be performed when input power is no
longer being provided. In this case, the sensor 12 and associated
alarming circuitry may operate on battery power for carrying out
the security scan.
[0034] FIG. 10 schematically illustrates one embodiment of a sense
loop circuit 55 defined between the alarming circuitry or a central
processing unit (CPU) and the recoiler 18. In this embodiment, the
sense loop circuit 55 includes a plurality of resistors R
comprising a voltage divider network. One or more resistors R may
be disposed in both the sensor 12 and the recoiler 18. The resistor
R in the recoiler 18 may be disposed across the pair of conductors.
The sense loop circuit 55 may be further defined by the pair of
conductors 50 extending through the tether 14. If the tether is cut
or disconnected, the total resistive load detected by the alarming
circuitry and/or the CPU changes.
[0035] FIG. 11 shows a graph depicting the voltage in the sense
loop circuit 55 when the tether 14 is intact (i.e., not cut or
removed) and there is a loss of electrical power, for example as a
result of a power outage. As shown, the voltage in the sense loop
circuit 55 is about 1.4 volts. FIG. 12 shows a graph depicting the
voltage in the sense loop circuit 55 when the tether 14 has been
cut (whether partially or completely) or removed (e.g.,
disconnected or detached). As shown, the voltage in the sense loop
circuit 55 is about 2.4 volts. Thus, the detected voltage level is
higher when the tether 14 has been cut or removed (e.g.,
disconnected or detached). FIG. 13 shows another graph depicting
the voltage in the sense loop circuit 55 where an intact and
connected tether 14, indicated as a "good cable" in FIG. 13, has a
lower voltage than a cut or removed (e.g., disconnected or
detached) tether, indicated as a "bad cable" in FIG. 13.
[0036] In one embodiment, the security scan commences immediately
after power is lost. For example, input power may be provided at
about 18 volts, and when power is lost, the detected voltage would
be 0 volts. The merchandise security system 10 may include
capacitors that do not allow for a sudden drop in voltage, but
there is typically a delay before the voltage level drops to the
lower level. As the capacitors discharge, the voltage level passes
from the initial input power (e.g., about 18 volts), to the "bad
cable" range (e.g., about 2.4 volts), and to the "good cable" range
(e.g., about 1.4 volts). If the security scan was performed
immediately after the power is lost and the tether 14 was intact
and connected, the "bad cable" range would be detected, and the
tether would be incorrectly indicated as cut or disconnected.
However, it is understood that if the scan is initiated immediately
after power ceases, the alarming circuitry and/or CPU is able to
compare the measured voltage level and the expected voltage level
during the voltage decay period. If the measured and expected
voltage levels are within a predetermined range during the decay
period following a power loss, an alarm is not generated.
[0037] FIG. 14 shows a graph depicting another example of the
voltage in the sense loop circuit 55 where the voltage level is
initially at about 18 volts and thereafter the input power ceases
at about 3.0 seconds. There is a sharp decline in the voltage level
to about 6.8 volts at about 3.3 seconds. This drop may occur in
about 250 ms. Then the voltage drops further to about 1.5 volts at
about 5.3 seconds, wherein the further drop takes about 2 seconds.
FIG. 15 shows a similar graph depicting another example of the
voltage in the sense loop circuit 55 where the voltage level is
initially at about 18 volts and thereafter the input power is lost.
FIG. 15 demonstrates that a security scan may be initiated after a
predetermined period of time and after the voltage transition so
that false alarms are reduced. In this example, there is about 3
seconds after power is lost before the security scan begins.
[0038] FIG. 16 shows a flowchart of an embodiment of a method 60
for determining the integrity and connection of the tether 14
according to the present invention. In the illustrated embodiment,
the alarming circuitry and/or CPU may be configured to initially
determine whether a voltage level is equal to about "X" volts, as
indicated by reference character 62. For example, "X" volts may be
the normal input voltage provided, such as about 18 volts. If the
voltage is equal to "X" volts, there is no alarm event. If the
voltage does not equal "X" volts, a security scan is initiated, as
indicated by reference character 64. The security scan may be
cyclical in that the scan may be performed repeatedly in
predetermined increments of time. The security scan may be
initiated immediately after power ceases, or alternatively, after a
predetermined delay (e.g., about 2-4 seconds), as discussed above,
to allow the voltage in the tether 14 to decay. The security scan
may first determine whether the tether 14 has been shorted (e.g.,
the conductors 50 are crimped together), as indicated by reference
character 66. In the case that the tether 14 is shorted, the
voltage level will be zero, or close to zero, and an alarm signal
will be generated, as indicated by reference character 76. In one
embodiment, a cycle of the security scan may be about 200 ms in
duration to determine whether the tether 14 is shorted.
[0039] If the tether 14 is not shorted, the alarming circuitry or
CPU may generate an electrical signal on the pair of conductors 50,
as indicated by reference character 68. For example, the electrical
signal could be a ping, current, pulse, frequency, or the like. In
one embodiment, generating an electrical signal may include setting
the bit high on one of the conductors 50 to the alarming circuitry
and/or CPU and waiting for the tether 14 to charge. For example,
the bit may be set to about 3.0 volts. FIGS. 11 and 13 show that
the bit may be set high at time "T1" and then a pause is
effectuated (e.g., about 250 ms). The voltage level in the tether
14 is then determined, and if the voltage level is greater than "Y"
volts (e.g., about 2.0 volts), as indicated by reference character
70, the security scan is repeated at least one more time, as
indicated by reference character 72. If the voltage level is still
greater than "Y" volts, as indicated by reference character 74, an
alarm signal is generated, as indicated by reference character 76.
However, if the voltage level is not greater than "Y" volts, either
after the first measurement or the second measurement, the security
scan is restarted, as indicated by reference character 64, and no
alarm signal is generated.
[0040] It is understood that the voltage levels and scanning
intervals may be any desired value in order to determine whether to
generate an alarm signal and that the aforementioned values are
intended only as examples to illustrate the broad principles and
concepts of the invention. The determined voltage level may be
analog levels (ADC readings), although other values or levels may
be determined in order to perform the aforementioned method 60. In
addition, it is understood that the steps of the flowchart shown in
FIG. 16 are meant for illustrative purposes only and that the steps
may be performed in any desired order and that certain steps may be
combined or eliminated in various embodiments. For example, the
step 66 of determining if the tether 14 is shorted may be
eliminated, as the step 70 of determining the voltage level "Y"
after the step 68 of generating an electrical signal may be used to
determine if the tether 14 has been shorted.
[0041] The foregoing has described one or more embodiments of
merchandise security systems and methods for displaying and
protecting an article of merchandise from theft. Those of ordinary
skill in the art will understand and appreciate that numerous
variations and modifications of the invention may be made without
departing from the spirit and broad scope of the invention.
Accordingly, all such variations and modifications are intended to
be encompassed by the appended claims.
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